Percussion chatter hammer drill



ilzuq ATTORNEYS A. E. BARDWELL PERCUSSION CHATTER HAMMER DRILL Filed Aug.

Nov. 5, 1968 nus E. Bneowsu, 2

United States Patent 3,409,095 PERCUSSION CHATTER HAMMER DRILL Allen E. Bardwell, East Brunswick, N.J., assignor to Trident Industries, Inc., Princeton, N.J., a corporation of Delaware Filed Aug. 7, 1964, Ser. No. 388,047

. 13 Claims. (Cl. 175-499 The present invention relates generally to drills, and more particularly to a novel percussion chatter hammer drill of the gravity drop type and to a novel method of drilling.

Gravity drop drilling is an old art. Back through the years, many efforts have been made to improve the time required to drill a hole or shaft, attention having been given to internal mechanisms of drill elements, quality and type of drill bits, methods and other facts. Many patents have been granted on internal structures of gravity drop drill elements for multiplying drilling blows per cycle, but in the -applicants knowledge, none have been successful in withstanding the rugged requirements of gravity drop drilling. Manifestly, in order to achieve commercial success in the drilling field, a drill must give service over a predetermined period of time to enable the user to recover with profit his capital invention. Percussion hammer drills are more expensive than standard or conventional drills using a solid drill stem, hence, there must be an increased percentage of drilling depth over an extended period of time to achieve practical success.

Therefore, an object of the present invention is to provide a gravity drop percussion chatter hammer drill which is a practical commercially acceptable solution to the above-outlined problem long existing in the drilling industry.

In brief, a preferred embodiment of the present novel percussion hammer drill comprises an elongated casing, an attachment unit extending into and integrated with the top of the casing for receiving a cable or jar, an anvil and bit attachment unit extending into and integrated with the bottom of the casing, a reciprocatable hammer unit disposed within the casing for drilling engagement with the anvil unit, and a heavy compression spring biasing the hammer unit into predetermined positions in respect to the anvil unit. The present novel method includes delivering "multiple blows per cycle in a manner to provide cumulative stresses in the rock material to substantially increase the drilling results. 7

Hence, a further object of the present invention is to provide a percussion hammer drill of the type indicated above which has greatly increased drilling speed and efiiciency as compared with gravity drills of conventional structure.

Another object is to provide a novel method of cable drilling whereby the drilling results per cycle are substantially increased.

Another object is to provide a novel method of cable drilling in which rock material is stressed and then shattered while under an initial stress.

Another object is to provide a novel percussion hammer drill capable of producing during each drilling cycle at least one percussive stroke to increase the drilling effect of the tool beyond that of a conventional gravity drop unit.

Other objects are to provide a novel percussion hammer drill of the gravity type which is capable of materially increasing the drilling penetration per drilling cycle, which is of simplified internal construction thereby materially decreasing possibilities of malfunctioning, which is of rugged construction over-all, enabling the drill to function as intended over a relatively long period of time and under the rigorous conditions of gravity drop drilling,

which requires substantially no maintenance over a relatively long period of time, which requires no special skill on the part of an operator to accomplish the intended increased drilling effect of the drill, which can be utilized to its maximum efficiency with minimum instructions to operating personnel, which is commercially practical and economical in comparison with conventional and other drop drills, which can be more quickly released from a stuck position by jars than a conventional drill, which is much more effective in reaming than a conventional'drill, which gets twice more drilling footage with substantially the same wear on the bit, and which otherwise fulfills the objects and advantages sought therefor.

The foregoing and other objects and advantages are apparent from the following description taken with the accom anying drawings, in which:

FIGURES 1, 2 and 3 comprise a longitudinal, diametric cross-sectional view through a percussion hammerdr'ill illustrated as formed of metal incorporating the principles of the present invention, FIGURE 1 including the upper portion thereof, FIGURE 2 the central portion, and FIGURE 3 the lower portion, portions of elements or units in all three figures being in elevation.

Referring to the drawings more particularly by reference numerals, 10 indicates generally a percussion hammer drill incorporating the teachings of the present invention. Broadly, the drill 10 includes a casing 12, an anvil unit 14, a rope socket or jar attaching unit 16, a hammer unit 18, a heavy compression spring 20, and an upper bearing 22 and a lower bearing 24 for the hammer unit 18.

The rope socket or jar attaching unit 16 is of solid construction and of the configuration shown in the drawings, a portion 26 thereof extending into the top of the casing 12 and being welded thereto circumferentially at 28. A portion 30 threadedly receives a cable, a jar, or cable attachment unit, not shown.

The anvil unit 14 is also of solid construction and of the configuration shown in the drawings, a portion 32 thereof extending upwardly into the casing 12 and is shrunk fitted and Welded thereto circumferentially at 34. An integral anvil cap 36 extends upwardly from the anvil portion 32 within a debris chamber 38. A threaded bit socket 40 removably receives a bit of selected design.

The hammer unit 18 includes a heavy elongated cylindrical body 42, an upper reduced integral cylindrical portion 44 which reci rocates within the bearing 22, and a lower reduced cylindrical integral portion 46 which reciprocates in the lower bearing 24. The compression spring 20 surrounds the hammer portion 46 above the bearing 24, said spring 20 abutting the shoulder at the juncture of the main body portion 42 and the reduced portion 46 and the top end of the bearing 24, as is clear from FIG- URES 2 and 3. The faces of the anvil cap 36 and the hamportion 46 are hardened.

In a commercial exemplification of the present percussion hammer drill 10 in use in Water well drilling, the hammer unit 18 has a weight of approximately five hundred pounds, and the total weight of the casing 12, the anvil unit 14 and the attachment unit 16 is approximately five hundred pounds. The spring 20 has a force of approximately six hundred pounds, which is sufiicient to maintain the bottom face of the hammer portion 46 spaced substantially one-quarter inch from the anvil cap 36. As the tool 10 is raised from the bottom of the hole by any cable rig, the spring 20 is compressed and the hammer unit 18 rests with the hammer portion 46 in engagement with the anvil cap 36. When the string of tools of which the present percussion hammer drill is a part reaches the top of the pickup stroke, for a moment, it is, in effect weightless. At this point, the spring 20 is effective to thrust the hammer unit 18 up and off the anvil cap 36 about one-quarter inch. As the tool fallsan average of about twenty-eight inches under the force of gravity, the hammer unit 18 is held out of engagement with the anvil cap 36 in a cocked position by the force of the spring 20. To prevent the hammer unit 18 from rising more than the predetermined distance of approximately one-quarter inch off the anvil cap 36, the shoulder at the juncture of the reduced portion 44 and the main body 42 engages the lower end of the bearing 22 which acts as a snubber. For hard rock, the effectiveness of the hammer blow is reduced as the distance between the lower face of the hammer portion 46 and the anvil cap 36 increases above approximately one-quarter inch, so that the effective range for increased drilling is a gap of between approximately one-eighth inch and one inch. For shale or soft rock, the maximum gap may be extended to as much as three inches, since the bit on the gravity drop blow will penetrate relatively much further so that the time interval for the percussion blow or blows is greater. A short gap reduces peening of hammer and anvil to a minimum.

When a bit mounted in the socket 40 strikes the bottom of the hole at the end of a gravity drop, the hammer unit 18 continues its downward thrust with a force of mass times velocity squared. This blow of the hammer unit 18 is synchronous, in fact, almost simultaneous with the gravity blow of the bit. The force of the second blow or blows under many drilling operations is substantially equal or greater in shearing or cutting force to that of the gravity blow, drillers today employing the present tool 10 getting up to and over one hundred percent more depth with the present tool 10 in their string of cable tools than when employing the conventional sinker bar or drill stem. In some rock formations, the percentage increase is much greater than one hundred percent. For most effective drilling results, the hammer unit 18 should strike the anvil cap 36 while the bit is still substantially on the bottom of the hole and in its forward cutting position of movement. This is true because, as the bit strikes the bottom of the hole, the rock is compressed, in effect, by the chisel bit edge under the weight of the anvil casing, attachment unit, and jars, if any. As the chisel bit compresses the rock, it creates stresses in the rock formation. Before these stresses can be relieved by the bit and string of tools bouncing away from the rock, the hammer unit 18 strikes the anvil cap 36 thereby creating a second wave of stresses in the already stressed rock to shatter the same. The combined effect produces increased rock penetration per cycle. For best results, the percussion blow or blows occur as the gravity blow stresses are substantially maximum. No time is lost in the drilling cycle, since there is no delay in raising the string of tools after the gravity blow or strokes of the bit. Hard rock cuttings are more coarse due to high rate of cutting power created by the backup stroke, or strokes. In softer formation, the hammer has opportunities to strike and rebound several times, as can be felt in the cable during drilling, since the bit has a longer penetrating distance.

The present tool may be used in oil and other drilling. In oil drilling, the masses of the elements are greatly increased as a general rule. Of course, in water well drilling, the masses can be increased or decreased, and the size changed.

Extensive tests with the present drill have demonstrated that jars are more effective with it than with the standard solid drill stem in breaking a string of tools loose from a seam, that reaming of the hole, which becomes necessary when the hole becomes tapered as the bit wears, is much more rapid with the present drill than with a solid drill stem. In fact, the present commercially successful cable drop drill is the first major advance and improvement in cable drop tools since long before the turn of the century, solid drill stems having been used these many years.

It is apparent that there has been p v d a novel drill 10 and a novel method of drilling which are highly effective for their intended purposes as a commercially acceptable unit and method.

It is to be understood that the foregoing description and the accompanying drawings have been given by way of illustration and example. It is also to be understood that changes in form of the elements, rearrangement of parts and steps, and substitution of equivalent elements or steps, which will be obvious to those skilled in the art, are contemplated as within the scope of the present invention which is limited only by the claims which follow.

What is claimed is: I

1. In combination, a cable drop percussion hammer drill comprising a casing, a stationary anvil extending into and fixed to said casing, a hammer reciprocably mounted in said casing for engagement with said anvil, compressible means biasing said hammer away from said anvil to hold the hammer from the anvil as the drill is lowered and which is overcome by the hammer upon the drill striking a hole bottom, said compressible means being yieldable to permit said hammer to strike said anvil immediately after the drill strikes the bottom of a hole, means closing the upper end of said casing, and means for lifting said drill.

2. The combination of claim 1 in which the reciprocating travel of said hammer is substantially one-quarter inch.

3. In combination, a cable drop percussion hammer drill comprising a casing, a hammer reciprocably mounted in said casing, stop means in said casing for limiting upward movement of the hammer, an anvil in fixed stationary relation to said casing disposed for striking engagement by said hammer, compressible means biasing said hammer away from said anvil and towards said stop means, said compressible means being adapted to maintain said hammer against said stop means as the drill is gravity dropped, means for attaching a bit to said drill, and means for attaching lifting means to said drill.

4. The combination of claim 2 in which the reciprocating travel of said hammer is substantially one-quarter inch.

5. The combination of claim 3 in which said compressible means is capable of exerting a force sufiicient to maintain said hammer a predetermined distance away from said anvil as the drill is gravity dropped and which is compressed by the hammer upon the drill striking a hole bottom.

6. The combination of claim 5 in which said compressible means is a compression spring.

7. The combination of claim 5 in which the gap between the faces of the hammer and anvil is between oneeighth inch and one inch for drilling hard rock when the mass of the hammer is approximately five hundred pounds.

8. The combination of claim 5 in which the gap between the faces of the hammer and anvil is between approximately one inch and three inches for drilling shale and soft rock when the mass of the hammer is approximately five hundred pounds.

9. In a percussion hammer drill of the gravity drop type, the combination comprising: a hollow, enclosed casing tightly capped to deter the entrance of liquid and having an anvil unit in fixed relation to the casing which receives a drill bit and presents an anvil surface in the interior of said casing; a hammer unit movable within said casing which includes a hammer portion facing said anvil surface that alternately strikes the same and moves away from the same as the hammer unit moves downward and upward with respect to the casing; a spring interposed between the casing and the hammer unit urging the hammer unit upward to establish a gap between said anvil surface and said hammer portion, which spring acts as the sole means for holding the hammer in an upper position establishing said gap during a gravity drop of the drill, and which is overcome by the mass of said hammer unit upon dropping and then abruptly decelerating said casing, whereby said hammer unit strikes said anvil surface; and a snubber within said casing limiting upward movement of the hammer unit with respect to said casing to define the extent of said gap during descent of the drill.

10. A hammer drill as in claim 9 wherein said snubber constftufes a solid abutment against which said hammer unit is arrested in its relative upward movement with respect to said casing.

11. A hammer drill as in claim 9 wherein the mass of the hammer unit is substantially one-half the mass of the entire drill.

12. In a percussion hammer drill, the combination comprising: a hollow, elongate casing that is tightly enclo;ed to deter entrance of liquid; an anvil unit attached to and fixed with respect to the casing for movement therewith, said anvil unit presenting an anvil surface within the casing; means within said casing having an abutment surface that limits the upward movement of a hammer unit with respect to the casing and said anvil surface; an oscillatable hammer unit within said casing freely slidable without locking attachment between a lower position bearing against said anvil surface and an upper position bearing against said abutment surface; and resilient means interposed between said casing and said hammer unit urging the hammer unit upward against said abutment surface and holding it in such position during a gravity drop of the drill, said resilient means presenting an upward force that is overcome by the energy of said hammer upon a striking of the drill on a hole bottom at the end of a gravity drop whereby the hammer compresses the resilient means and delivers a blow to said anvil unit.

13. A percussion hammer drill as in claim 12 in which the total stroke of said hammer unit between bearing engagement with said anvil surface and said abutment surface is within one-eighth to three inches.

References Cited UNITED STATES PATENTS 2,738,956 3/1956 Bielstein 173-121 2,765,776 10/1956 Pyk 173118 2,835,474 4/1958 OConnor et al 175-299 2,872,158 2/1959 Green 175-299 2,998,087 8/1961 Iddings 173-118 3,303,899 2/1967 Jones et al. 175-299 3,305,034 2/1967 Koeln 175299 3,307,641 3/1967 Wiggins 17556 JAMES A. LEPPINK, Primary Examiner. 

1. IN COMBINATION, A CABLE DROP PERCUSSION HAMMER DRILL COMPRISING A CASING, A STATIONARY ANVIL EXTENDING INTO A FIXED TO SAID CASING, A HAMMER RECIPROCABLY MOUNTED IN SAID CASING FOR ENGAGEMENT WITH SAID ANVIL, COMPRESSIBLE MEANS BIASING SAID HAMMER AWAY FROM SAID ANVIL TO HOLD THE HAMMER FROM THE ANVIL AS THE DRILL IS LOWERED AND WHICH IS OVERCOME BY THE HAMMER UPON THE DRILL STRIKING A HOLE BOTTOM, SAID COMPRESSIBLE MEANS BEING YIELDABLE TO PERMIT THE DRILL STRIKE AND ANVIL IMMEDIATELY AFTER THE DRIL STRIKES THE BOTTOM OF A HOLE, MEANS CLOSING THE UPPER END OF SAID CASING, AND MEANS FOR LIFTING SAID DRILL. 